Simian hemorrhagic fever is an endemic disease in feral E. patas monkeys (10%). The agent has been found occasionally in feral Papio cynocephalus and Cercopithecus aethiops monkeys. The disease among Asian Macaque monkeys is caused by a laboratory accident, usually transmitted by contamined needles. A highly specific complement fixation test has been developed using antisera from hyperimmunized guinea pigs. The test can detect antigen in the sera of acutely ill Macaque monkeys as well as chronically infected E. patas and Cercopithecus aethiops monkeys. Polyinosinic polycytidylic acid (Poly I Poly C complex), is an effective interferon inducer and antiviral agent in Rhesus monkeys. The complex can be used prophylactically but not therapeutically in SHF infections of Rhesus monkeys.